Field
The described technology generally relates to a flexible display device.
Description of the Related Technology
A typical display device has a structure in which a cover window is bonded to the whole surface of a display panel. When manufacturing a bendable and stretchable flexible display device, the cover window is formed of a plastic film such as polyethylene terephthalate (PET), polycarbonate (PC), polyimide (PI), poly(methylmethacrylate) (PMMA), and the like. In addition, a hard coating layer is provided above the cover window to realize sufficient hardness of the window surface. However, the hard coating layer can realize the hardness but not enable sufficient stretchability.
In order to satisfy the hardness constraint, which is a desired characteristic of the window, a resin material such as an acryl-based resin or an epoxy-based resin and an organic/inorganic-based additive are mixed through functional coating to form a hard coating layer using a UV curable hard coating method. However, the hard coating method for hardness increase of the window has characteristics of glass so that stretching is impossible. Also, even though the window layer is stretched, the window cannot properly function due to delamination between the window layer and the hard coating layer. That is, a combination structure of the window layer and the hard coating layer applied to the flexible display device has a limit in realization of a structure that can increase hardness and satisfy a desired level of elongation or stretching.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it can contain information that does not constitute the prior art that is already known in this country to a person of ordinary skill in the art.